There are methods currently available to identify one or more monomers of a biomolecule. Monomers may comprise elements of biomolecules, such as amino acid monomers which are included in a protein, nucleotide monomers which are included in a nucleic acid, and monosaccharide monomers which are included in a sugar chain. As a monomer identifying method, there are identification methods using monomer measurement where light or electricity is used as a probe signal, for example. In a monomer identifying method using monomer measurement, a specific monomer can be detected by modifying a target sample with a fluorescent molecule or a probe molecule having electroactivity. For example, sequences for proteins have been determined by using various methods, such as high performance liquid chromatography (HPLC) based on enzymatic degradation, mass spectrometry, X-ray crystal structure analysis, and Edman degradation, for example.
However, the aforementioned methods for detecting a monomer by modifying the sample with a probe molecule have problems in that a chemical modification may be required and that the efficiency with any such modification may be insufficient. Moreover, the aforementioned methods can only detect specific chemical species and may not be applied to a biomolecule sequencing process conducted using a bio-sample containing various molecular species.